'Afternoon Rynn . . . :^) Nice looking light beams. I've tried playing around many times, to get the same type of light beams underwater, but I never succeeded. I'll follow your instructions & see if I can duplicate them. What I don't understand is: 1st, why you have to have a terrain in the background, so the light beams will be solid from top to bottom? 2nd, Why you don't get the same effect by using a "procedural color" caustic, that you do when you use a "mapped picture" caustic, there both images? 8^o Anyway, thanks for the information & you have a good one . . . Mark. ;^)